ynonym\nfor the standard SQL function STDDEV_POP(), provided as a MySQL\nextension.\n\nIf there are no matching rows, STD() returns NULL.\n\nURL: http://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html\n\n','','http://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html');